Conventionally, a cellulose powder has been widely used as an excipient in preparation of a molded article containing an active ingredient in the fields of pharmaceutical, food and other chemical industries.
A single inorganic compound, however, is restricted in terms of the amount thereof which can be powdered at one time, because of being too large in apparent specific volume. In addition, such an inorganic compound also has the handing problem of being scattered, for example. Therefore, there is studied use of a porous composite particle of cellulose and an inorganic compound, as an excipient.
In a common tablet production method, tableting is made in which a powder is packed in a mortar and subjected to compression molding by a pestle. If a drug is easily attached to the pestle, a phenomenon called “sticking” occurs in which the surface of a molded article is peeled off. While a single inorganic compound is usually used as an excipient, sticking cannot be necessarily prevented by the single inorganic compound. In addition, the single inorganic compound is large in apparent specific volume, and thus is known to have the following problems: easily causes a jet flow during tableting and deteriorates packability in the mortar, resulting in a variation in the weight of a molded article; and a phenomenon called “capping” occurs in which a molded article is partially peeled off.
A cellulose powder, although serving as an excipient high in moldability, is also known to have the following problems: if wetted once, the cellulose powder is deteriorated in moldability and does not exert a function as an excipient; and the cellulose powder is low in liquid retention property as compared with an inorganic compound.
Patent Literature 1 describes a method of providing a composite particle having an apparent specific volume of from 7 to 13 cm3/g, the method including forming and drying a slurry including cellulose and calcium silicate at a specified mass ratio. Patent Literature 1 describes the following: the composite particle is high in liquid retention rate and is high in particle fluidity after liquid retention and thus can be tableted in open feed by a direct tableting method, less causes tableting failure to occur, and is high in moldability.